GM / Chevy LR4 (Vortec 4800)

GM / Chevy LR4 (Vortec 4800)The GM / Chevy LR4 is a 4.8 l (293 cu.in.) natural aspirated V8 90° four-stroke gasoline engine from a Generation III small block V8 truck engine series. The engine was produced in St. Catharines, Ontario and Romulus, Michigan. from 1999 to 2006. The LR4 4.8 L engine is also called Vortec 4800. This engine was the replacement for the GM L30 (5.0 L).

The GM LR4 (Vortec 4800) features V8 90° cast-iron cylinder block with a five-bearings crankshaft, two aluminum heads, single one-piece cast camshaft and two valves per cylinder (16 in total). The LR4 has a sequential multi-port fuel injection system and 78.0 mm (3.07 in) throttle body. The engine used a “Coil-Near-Plugs” ignition system.

Compression ratio rating is 9.4:1. Cylinder bore and piston stroke are 96.0 mm (3.78 in) and 83.0 mm (3.27 in), respectively. The engine produced from 258 PS (190 kW; 255 HP) to 290 PS (213 kW; 285 HP). The maximum torque is 386 Nm (39.4 kg·m; 284.9 ft·lb) – 400 Nm (40.8 kg·m; 295.2 ft·lb).

General information

Engine Specifications
Engine codeGM / Chevy LR4 (Vortec 4800)
LayoutFour stroke, V8
Fuel typeGasoline (petrol)
Production1999-2006
Displacement4.8 L, (293 cu in)
Fuel systemSequential multi-port fuel injection
Power adderNone
Power output 258 PS (190 kW; 255 HP)
273 PS (201 kW; 270 HP)
290 PS (213 kW; 285 HP)
Torque output 386 Nm (39.4 kg·m; 284.9 ft·lb)
400 Nm (40.8 kg·m; 295.2 ft·lb)
Firing order1-8-7-2-6-5-4-3
Dimensions (L x W x H):
Weight

Cylinder block

The LR4 has a cast-iron cylinder block with a five-bearings crankshaft supported system. The crankshaft journal diameter is 65.0 mm (2.55 in), the crankpin diameter is 53.3 mm (2.09 in).

The cylinder bore is 96.0 mm (3.78 in), piston stroke is 83.0 mm (3.27 in) and compression ratio rating is 9.4:1. The GM LR4 motor has two compression and one oil control rings. The connecting rod’s length is 159.38 mm (6.275 in)

Cylinder block
Cylinder block alloyCast-iron
Compression ratio:9.4:1
Cylinder bore:96.0 mm (3.78 in)
Piston stroke:83.0 mm (3.27 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:5
Cylinder inner diameter (standard):96.000-96.018 mm (3.7795-3.7802 in)
Piston skirt diameter (standard):96.000 mm (3.7795 in)
Piston pin outer diameter:23.997-24.000 mm (0.9448-0.9449 in)
Piston ring side clearance:Top0.045-0.080 mm (0.0018-0.0031 in)
Second0.040-0.078 mm (0.0016-0.0031 in)
Oil0.012-0.200 mm (0.0005-0.0079 in)
Piston ring end gap:Top0.23-0.44 mm (0.0091-0.0173 in)
Second0.44-0.70 mm (0.0173-0.0276 in)
Oil0.18-0.75 mm (0.0071-0.0295 in)
Connecting rod small end diameter24.000 mm (0.9449 in)
Connecting rod big end diameter:56.505-56.525 mm (2.2246-2.2254 in)
Connecting rod center distance:159.38 mm (6.275 in)
Crankshaft main journal diameter:64.993-65.007 mm (2.5588-2.5593 in)
Crankpin diameter:53.318-53.338 mm (2.0991-2.0999 in)
Crankshaft center distance:41.5 mm (1.635 in)

Cylinder head

The cylinder heads are made of strong, light aluminum alloy which gives it good cooling efficiency. The camshaft is driven by a single chain. The timing chain transmits the rotational movement from the crankshaft to the camshafts. Valves are operated via pedestal mounting rocker arms.

The intake valve diameter is 48.0 mm (1.8898 in) the exhaust valve diameter is 39.4 mm (1.5512 in), respectively. The intake duration is 190°, and the intake valve lift is 11.60 mm (0.457 in), the exhaust duration is 191°, the exhaust valve lift is 11.84 mm (0.466 in).

Cylinder head
Block head alloyAluminium
Valve Arrangement:OHV, chain drive
Cylinder head height:120.2 mm (4.7323 in)
Valves:16 (2 valves per cylinder)
Intake valve timing:190°
Exhaust valve timing:191°
Valve head diameter:INTAKE48.0 mm (1.8898 in)
EXHAUST39.4 mm (1.5512 in)
Valve length:INTAKE
EXHAUST
Valve stem diameter:INTAKE7.955-7.976 mm (0.3132-0.314 in)
EXHAUST7.955-7.976 mm (0.3132-0.314 in)
Valve spring free length:INTAKE52.9 mm (2.0827 in)
EXHAUST52.9 mm (2.0827 in)
Camshaft lobe lift:INTAKE6.96 mm (0.274 in)
EXHAUST6.82 mm (0.2685 in)
Camshaft journal diameter:54.99-55.04 mm (2.165-2.1669 in)

Head tightening procedure and torque specs:

  • Step 1: 30 Nm (3.06 kg·m; 22.14 ft·lb)
  • Step 2: Turn all bolts: 90°
  • Step 3: Turn all bolts excluding the medium length bolts at the front and rear of each head: 90°
  • Step 4: Turn all medium length bolts at the front and rear of each head: 50deg;

Maintenance data

Valve clearance (HOT)
Compression pressure
Standard12.5 kg/m2 / 300 rpm
Minimun7.0 kg/m2 / 300 rpm
Compression differential limit between cylinders1.0 kg/m2 (15 psi) / 300 rpm
Oil system
Oil consumption , L/1000 km (qt. per miles)up to 0.5 (1 qt. per 1200 miles)
Recommended engine oil 5W-30, 10W-30
Oil type API
Engine oil capacity (Refill capacity)5.7 L (6.02 US. qt, 5.02 Imp. qt.)
Oil change interval, km (miles)12,000 km (7,500 miles)
Oil Pressure 41 kPa at 1,000 rpm
124 kPa at 2,000 rpm
165 kPa at 4,000 rpm
Ignition system
Spark plugAC Delco: 41-985 Iridium
Spark plug gap1.01 mm (0.0398 in)

Vehicle applications

ModelYears Produced
Chevrolet Silverado 15001999-2006
GMC Sierra 15001999-2006
Chevrolet Tahoe2000-2006
GMC Yukon2000-2006
Chevrolet Express2003-2006
GMC Savana2003-2006
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